Engineering fire blight resistance into the apple cultivar 'Gala' using the FB_MR5 CC-NBS-LRR resistance gene of Malus × robusta 5

• Published in: Plant biotechnology journal Vol. 12; no. 6; p. 728
• Main Authors: Broggini, Giovanni A L, Wöhner, Thomas, Fahrentrapp, Johannes, Kost, Thomas D, Flachowsky, Henryk, Peil, Andreas, Hanke, Maria-Viola, Richter, Klaus, Patocchi, Andrea, Gessler, Cesare
• Format: Journal Article
• Language: English
• Published: England 01-08-2014
• Subjects: Crosses, Genetic; Disease Resistance - immunology; Erwinia amylovora - pathogenicity; Erwinia amylovora - physiology; Genes, Plant; Genetic Engineering - methods; Malus - genetics; Malus - immunology; Malus - microbiology; Plant Diseases - immunology; Plant Diseases - microbiology; Plants, Genetically Modified; Reverse Transcriptase Polymerase Chain Reaction; Virulence; Gene-for-gene; GMO; Erwinia amylovora
• ISSN: 1467-7652
• DOI: 10.1111/pbi.12177

The fire blight susceptible apple cultivar Malus × domestica Borkh. cv. 'Gala' was transformed with the candidate fire blight resistance gene FB_MR5 originating from the crab apple accession Malus × robusta 5 (Mr5). A total of five different transgenic lines were obtained. All transgenic lines were shown to be stably transformed and originate from different transgenic events. The transgenic lines express the FB_MR5 either driven by the constitutive CaMV 35S promoter and the ocs terminator or by its native promoter and terminator sequences. Phenotyping experiments were performed with Mr5-virulent and Mr5-avirulent strains of Erwinia amylovora, the causal agent of fire blight. Significantly less disease symptoms were detected on transgenic lines after inoculation with two different Mr5-avirulent E. amylovora strains, while significantly more shoot necrosis was observed after inoculation with the Mr5-virulent mutant strain ZYRKD3_1. The results of these experiments demonstrated the ability of a single gene isolated from the native gene pool of apple to protect a susceptible cultivar from fire blight. Furthermore, this gene is confirmed to be the resistance determinant of Mr5 as the transformed lines undergo the same gene-for-gene interaction in the host-pathogen relationship Mr5-E. amylovora.